Hip and knee pain

Referred hip pain

• May arise from expansion of AAA, intra-abdominal or pelvic tumors, diverticular disease, epidural abscess, psoas abscess, herpes zoster, herniated lumbar disc, abdominal wall/inguinal hernias
• May be referred from back or knee

Clues to diagnosis

• Determine precise location of pain to limit differential
• Determine activities that cause pain
• Complaints of ‘buckling’ or ‘giving way’ are usually due to pain and reflex inhibition rather than acute neurological emergency. May also represent patellar subluxation or ligamentous injury/joint instability
• Poor conditioning and weak quads causes anterior knee pain of patellofemoral syndrome
• Locking of knee suggests meniscal injury (acute or chronic)
• Popping sensation or sound at time of pain onset suggests ligamentous injury
• Recurrent knee effusion after activity suggests meniscal injury
• Pain at joint line indicates meniscal injury (maybe)

Psoas abscess

• Susceptible to haematogenous spread due to rich blood supply and proximity to overlying retroperitoneal lymphatics
• S. aureus (80%), Serratia, Pseudomonas, Haemophilus, Proteus and enteric pathogens
• Presents with abdominal pain radiating to the hip, flank pain, fever and limp
• Nausea, weight loss, malaise
• Hip flexion against resistance should provoke pain
• Diagnosis confirmed by CT

Regional nerve entrapment syndromes

• Lateral femoral cutaneous nerve entrapment (meralgia paraesthetica)
  • Nerve enters thigh under inguinal ligament near ASIS
  • Tight belts, heavy tool belts, car seat belts, corsets, pregnancy, certain sitting positions, focal trauma, appendectomy, hysterectomy and obesity
  • Pain, burning, hypersensitivity, paresthesia
  • Pain exacerbated by tapping near ASIS
  • Limit exacerbating activity and eliminate source of irritation
  • NSAIDs and weight loss can help

Regional nerve entrapment

• Obturator nerve entrapment
  • Typically a sequelae of pelvic fracture or abdominopelvic surgery
  • Pain in groin and down inner thigh aggravated by hip movement
• Ilioinguinal nerve entrapment
  • Innervates groin and scrotum or labia
  • Entrapment due to abdominal wall muscular hypertrophy or pregnancy
  • Hyperextension of hip produces pain and hypoesthesia in groin distribution
• Piriformis syndrome
  • Pain in buttocks or hamstring worsened by sitting, climbing stairs or squatting
  • Hip flexion and passive internal rotation will worsen symptoms
  • Treatment is conservative

Specific bursal syndromes of hip

• Bursal pain may be due to infection or inflammation in the setting of minor trauma, rheumatoid arthritis, psoriatic arthritis, ankylosing spondylitis, crystalline disease
• Gram stain positive and culture positive confirms infection but can have infectious bursitis without these findings and there is significant overlap with WCC counts and differentials

Trochanteric bursitis

• Between gluteus maximus and posterolateral greater trochanter with deep and superficial components
• Female runners with broad hips and elderly women (often with RA)
• Pain with hip abducted (deep bursa) or adducted (superficial bursa)
• Simple walking and stair climbing also exacerbate symptoms

Ischial or ischiogluteal bursitis

• Pain over sit bones
• Weaver’s bottom
• Lies close to sciatic nerve and posterior femoral cutaneous nerve predisposing to radicular pain

Iliopectineal bursitis

• Between hip joint and iliopsoas muscle
• Pain over anterior pelvis and groin
• Hip flexion and external rotation provides relief (like #)
• Extend hip and palpate over joint capsule to reproduce pain

Iliopsoas bursitis

• Lubricates iliopsoas tendon over lesser trochanter of femur
• Pain on extension of hip, reduced by hip flexion
• Tenderness over middle third of inguinal ligament near femoral pulse

Specific bursal syndromes of knee

• Pes anserine bursitis
  • Lies deep to tendinous insertion on medial aspect of tibia of semitendinosus, gracilis and sartorius
  • Lies above the medial collateral ligament insertion point
  • Seen in obese women with OA and runners
  • Anteromedial pain below joint line and focal swelling
• Prepatellar bursitis (housemaid’s knee)
  • Repetitive kneeling
  • Mild with effusion over lower pole of patella
  • Also a common site for septic bursitis, especially in children

Specific bursal syndromes of the knee

• Other knee bursa
  • Superficial infrapatellar bursa lies between tibial tubercle and skin
  • Deep infrapatellar bursa lies between patella and tibia
  • Neither of these are commonly inflamed unless infected
  • Medial collateral ligament bursa between ligament and knee capsule
  • Lateral collateral ligament bursa lies around ligament and can produce lateral knee pain when inflamed

Treatment of bursitis

• Inflammatory – NSAID’s, RICE
• Steroid injections into more readily accessible bursa helpful if infection ruled out
• Concomintant treatment for inflammatory and infectious bursitis is common with empirical treatment for S. aureus and strep while awaiting culture results
• Aspirations are fine but incision should not be performed in ED (risk of sinus formation)
• If fibrosis or synovial thickening occurs, excision of bursa can be performed

Myofascial syndromes (overuse)

• Hip overuse syndrome (external snapping hip syndrome)
  • In athletes get audible snapping sound as iliotibial band slips over greater trochanter with associated inflammation
  • Dancer’s hip in young women
  • Dynamic sonography and MRI are diagnostic but not crucial for diagnosis
• Fascia lata syndrome
  • Lateral thigh pain with palpation and trigger points
  • Get pain in anterior groin and point tenderness over anterior iliac crest
  • US confirms diagnosis

Myofascial syndromes (overuse)

• Patellofemoral syndrome (runner’s knee)
  • Focal trauma (least common), overuse and abnormal patellar tracking
  • Weak quads is a major contributor
  • More common in females due to Q angle >20 degrees due to broader pelvis
    • ASIS to central patella and central patella to tibial tuberosity
    • Females have 50-100% higher rate of knee injuries in general
  • Pain exacerbated by prolonged knee flexion (moviegoer syndrome), walking and especially stair climbing
  • Crepitus at patello-femoral joint suggests degeneration but may be normal
  • Conservatively managed with quad strengthening

Q angle

Myofascial syndromes (overuse)

• Chondromalacia patellae
  • Softening of cartilage on posterior surface of patella (typically with patellofemoral syndrome)
  • Pain on palpation of patella
  • Diagnosed surgically and impossible to distinguish clinically from patellofemoral syndrome
• Medial plica syndrome
  • Uncommon abnormal redundant folds of tissue which can lead to fibrous tissue formation at medial border of patella and anteromedial pain

Myofascial syndromes (overuse)

• Iliotibial band syndrome
  • Most common in long-distance runners and cyclists
  • Iliotibial band inserts on lateral femoral and tibial condyles with irritation of bursa underlying band
  • Pain reproduced at certain distance and tenderness over lateral epicondyles
  • Rest, decrease training distance, change shoes, stretching and local steroid injections

Myofascial syndrome (overuse)

• Popliteus tendinitis
  • Popliteus passes under lateral head of gastrocnemius assisting with internal rotation of tibia, withdrawing meniscus during flexion to prevent impingement and stabilises knee preventing forward displacement
  • Bursa separates tendon from underlying structures at lateral femoral condyle
  • Overuse of quads in athletes leads to posterolateral knee pain, worsened by running downhill
  • Tender in soft area at posterolateral knee between hard femur and tibia
  • Webb test: Internally rotate leg in supine patient, flex knee at 90 and ask patient to force external rotation against resistance. Positive = Pain

Myofascial syndromes (overuse)

• Patellar tendinitis
  • Inferior pole of patella pain from jumping
• Infrapatellar fat pad syndrome (Hoffa’s disease)
  • Fills anterior part of knee joint and held in place by patellar tendon, retinaculum and infrapatellar synovial plica inferiorly
  • Commonly inflamed with patellar tendinitis
  • Worse with leg straightening and walking up stairs
  • Conservatively managed

Myofascial syndromes (overuse)

• Quadriceps tendinitis
  • Proximal pole of patella
• Semimembranosus tendinitis
  • Posteromedial knee pain just distal to joint line
• Snapping knee syndrome
  • Iliotibial band again subluxing over lateral femoral condyle
  • Semitendinosus can also snap over medial condyle

Baker’s cyst

• Popliteal cyst
  • Posteroinferiorly due to distension of local bursa
  • In adults communicates with knee joint and associated intra-articular pathology is common
  • DDx includes DVT, aneurysms, vascular tumors, fibrosarcoma, lipoma
  • US is useful

Generalised arthropathy/tendinopathy

• Can be related to quinolones, corticosteroids, OCP, marijuana and cocaine

Avascular necrosis

• May be idiopathic or secondary
• Causes
  • Traumatic – Femoral neck fracture, hip dislocation, occult or minor trauma
  • Non-traumatic – Sickle cell, collagen vascular disease, alcohol abuse, renal transplant, SLE, dysbarism, chronic pancreatitis, exogenous steroids, Cushing’s, Caisson disease, Gaucher’s disease, renal osteodystrophy
• Plain X-ray: Mottled densities and lucencies through to severe collapse of femoral head
• CT and MRI helpful in establishing diagnosis

Osteomyelitis

• Infection of bone by bacteria or fungus resulting in bony destruction
• Contiguous spread (80%) or haematogenous (20%)
• Haematogenous more common in long bones (children) and vertebral bodies (adults)
• Pain + warmth, swelling, erythema (maybe)
• X-ray normal early then bone demineralisation, periosteal elevation and lytic lesions
• MRI has 95% sensitivity and bone biopsy confirms with certainty
• In diabetic feet, osteomyelitis more likely if skin ulceration >2cm, positive probe to bone test, ESR >70 or abnormal XR
• If blood culture negative, bone biopsy required to confirm organism

Osteomyelitis – risk factors

• Elderly – Haematogenous spread – S. aureus, H. influenzae – Van + PipTaz
• Sickle cell – Salmonella, Gram neg., S. aureus – Cipro +- vanc
• DM or vascular disease – S. aureus, Strep. Agalactiae, Strep. Pyogenes, coliforms, anaerobes (polymicrobial) – Vanc + PipTaz
• IVDU – S. aureus (MRSA), Pseudonomas – Vancomycin
• Developing nations – TB
• Newborn – S. aureus (MRSA), gram neg., GBS – Vanc + Ceftazidime
• Children – S. aureus (MRSA) – Vanc
• Post-operative – S. aureus, S. epidermidis – Vanc
• Human bite – Strep, anaerobes – PipTaz
• Animal bite – Pasteurella, Eikenella – PipTaz

Osteochondritis dissecans

• Portion of joint surface cartilage separates from underlying bone in knee
• Often occult trauma
• Lateral medial femoral condyle mostly
• Pain and swelling
• MRI diagnostic

Osteitis pubis

• Athletes with pain in pubis
• Typically duck-waddling gait and even rolling over in bed may be excruciating due to adductors and gracilis origin inflammation
• Rest and NSAID’s
• X-ray shows symmetric bone resorption medially, widening of pubic symphysis and sclerosis along pubic rami

Last Updated on October 6, 2020 by Andrew Crofton